Release js.FuncOf callbacks in wasm ssh and rdp to prevent leaks

client/wasm/internal/rdp/cert_validation.go

@@ -6,6 +6,7 @@ import (
 	"crypto/tls"
 	"crypto/x509"
 	"fmt"
+	"sync"
 	"syscall/js"
 	"time"
 
@@ -13,7 +14,7 @@ import (
 )
 
 const (
-	certValidationTimeout = 60 * time.Second
+	certValidationTimeout = 5 * time.Minute
 )
 
 func (p *RDCleanPathProxy) validateCertificateWithJS(conn *proxyConnection, certChain [][]byte) (bool, error) {
@@ -46,17 +47,31 @@ func (p *RDCleanPathProxy) validateCertificateWithJS(conn *proxyConnection, cert
 
 	promise := conn.wsHandlers.Call("onCertificateRequest", certInfo)
 
-	resultChan := make(chan bool)
+	resultChan := make(chan bool, 1)
-	errorChan := make(chan error)
+	errorChan := make(chan error, 1)
 
-	promise.Call("then", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
+	// Release from inside the callbacks so a post-timeout promise resolution
-		result := args[0].Bool()
+	// does not invoke an already-released func.
-		resultChan <- result
+	var thenFn, catchFn js.Func
+	var releaseOnce sync.Once
+	release := func() {
+		releaseOnce.Do(func() {
+			thenFn.Release()
+			catchFn.Release()
+		})
+	}
+	thenFn = js.FuncOf(func(this js.Value, args []js.Value) interface{} {
+		defer release()
+		resultChan <- args[0].Bool()
 		return nil
-	})).Call("catch", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
+	})
+	catchFn = js.FuncOf(func(this js.Value, args []js.Value) interface{} {
+		defer release()
 		errorChan <- fmt.Errorf("certificate validation failed")
 		return nil
-	}))
+	})
+
+	promise.Call("then", thenFn).Call("catch", catchFn)
 
 	select {
 	case result := <-resultChan:

client/wasm/internal/rdp/rdcleanpath.go

@@ -11,6 +11,7 @@ import (
 	"io"
 	"net"
 	"sync"
+	"sync/atomic"
 	"syscall/js"
 	"time"
 
@@ -57,6 +58,8 @@ type RDCleanPathProxy struct {
 	}
 	activeConnections map[string]*proxyConnection
 	destinations      map[string]string
+	pendingHandlers   map[string]js.Func
+	nextID            atomic.Uint64
 	mu                sync.Mutex
 }
 
@@ -66,6 +69,13 @@ type proxyConnection struct {
 	rdpConn     net.Conn
 	tlsConn     *tls.Conn
 	wsHandlers  js.Value
+	// Go-side callbacks exposed to JS. js.FuncOf pins the Go closure in a
+	// global handle map and MUST be released, otherwise every connection
+	// leaks the Go memory the closure captures.
+	wsHandlerFn  js.Func
+	onMessageFn  js.Func
+	onCloseFn    js.Func
+	cleanupOnce  sync.Once
 	ctx          context.Context
 	cancel       context.CancelFunc
 }
@@ -80,7 +90,11 @@ func NewRDCleanPathProxy(client interface {
 	}
 }
 
-// CreateProxy creates a new proxy endpoint for the given destination
+// CreateProxy creates a new proxy endpoint for the given destination.
+// The registered handler fn and its destinations/pendingHandlers entries are
+// only released once a connection is established and cleanupConnection runs.
+// If a caller invokes CreateProxy but never connects to the returned URL,
+// those entries stay pinned for the lifetime of the page.
 func (p *RDCleanPathProxy) CreateProxy(hostname, port string) js.Value {
 	destination := fmt.Sprintf("%s:%s", hostname, port)
 
@@ -88,7 +102,7 @@ func (p *RDCleanPathProxy) CreateProxy(hostname, port string) js.Value {
 		resolve := args[0]
 
 		go func() {
-			proxyID := fmt.Sprintf("proxy_%d", len(p.activeConnections))
+			proxyID := fmt.Sprintf("proxy_%d", p.nextID.Add(1))
 
 			p.mu.Lock()
 			if p.destinations == nil {
@@ -100,7 +114,7 @@ func (p *RDCleanPathProxy) CreateProxy(hostname, port string) js.Value {
 			proxyURL := fmt.Sprintf("%s://%s/%s", RDCleanPathProxyScheme, RDCleanPathProxyHost, proxyID)
 
 			// Register the WebSocket handler for this specific proxy
-			js.Global().Set(fmt.Sprintf("handleRDCleanPathWebSocket_%s", proxyID), js.FuncOf(func(_ js.Value, args []js.Value) any {
+			handlerFn := js.FuncOf(func(_ js.Value, args []js.Value) any {
 				if len(args) < 1 {
 					return js.ValueOf("error: requires WebSocket argument")
 				}
@@ -108,7 +122,14 @@ func (p *RDCleanPathProxy) CreateProxy(hostname, port string) js.Value {
 				ws := args[0]
 				p.HandleWebSocketConnection(ws, proxyID)
 				return nil
-			}))
+			})
+			p.mu.Lock()
+			if p.pendingHandlers == nil {
+				p.pendingHandlers = make(map[string]js.Func)
+			}
+			p.pendingHandlers[proxyID] = handlerFn
+			p.mu.Unlock()
+			js.Global().Set(fmt.Sprintf("handleRDCleanPathWebSocket_%s", proxyID), handlerFn)
 
 			log.Infof("Created RDCleanPath proxy endpoint: %s for destination: %s", proxyURL, destination)
 			resolve.Invoke(proxyURL)
@@ -142,6 +163,10 @@ func (p *RDCleanPathProxy) HandleWebSocketConnection(ws js.Value, proxyID string
 
 	p.mu.Lock()
 	p.activeConnections[proxyID] = conn
+	if fn, ok := p.pendingHandlers[proxyID]; ok {
+		conn.wsHandlerFn = fn
+		delete(p.pendingHandlers, proxyID)
+	}
 	p.mu.Unlock()
 
 	p.setupWebSocketHandlers(ws, conn)
@@ -150,7 +175,7 @@ func (p *RDCleanPathProxy) HandleWebSocketConnection(ws js.Value, proxyID string
 }
 
 func (p *RDCleanPathProxy) setupWebSocketHandlers(ws js.Value, conn *proxyConnection) {
-	ws.Set("onGoMessage", js.FuncOf(func(this js.Value, args []js.Value) any {
+	conn.onMessageFn = js.FuncOf(func(this js.Value, args []js.Value) any {
 		if len(args) < 1 {
 			return nil
 		}
@@ -158,13 +183,15 @@ func (p *RDCleanPathProxy) setupWebSocketHandlers(ws js.Value, conn *proxyConnec
 		data := args[0]
 		go p.handleWebSocketMessage(conn, data)
 		return nil
-	}))
+	})
+	ws.Set("onGoMessage", conn.onMessageFn)
 
-	ws.Set("onGoClose", js.FuncOf(func(_ js.Value, args []js.Value) any {
+	conn.onCloseFn = js.FuncOf(func(_ js.Value, args []js.Value) any {
 		log.Debug("WebSocket closed by JavaScript")
 		conn.cancel()
 		return nil
-	}))
+	})
+	ws.Set("onGoClose", conn.onCloseFn)
 }
 
 func (p *RDCleanPathProxy) handleWebSocketMessage(conn *proxyConnection, data js.Value) {
@@ -261,6 +288,7 @@ func (p *RDCleanPathProxy) handleDirectRDP(conn *proxyConnection, firstPacket []
 }
 
 func (p *RDCleanPathProxy) cleanupConnection(conn *proxyConnection) {
+	conn.cleanupOnce.Do(func() {
 		log.Debugf("Cleaning up connection %s", conn.id)
 		conn.cancel()
 		if conn.tlsConn != nil {
@@ -277,9 +305,32 @@ func (p *RDCleanPathProxy) cleanupConnection(conn *proxyConnection) {
 			}
 			conn.rdpConn = nil
 		}
+		js.Global().Delete(fmt.Sprintf("handleRDCleanPathWebSocket_%s", conn.id))
+
+		// Detach before releasing so late JS calls surface as TypeError instead
+		// of silent "call to released function".
+		if conn.wsHandlers.Truthy() {
+			conn.wsHandlers.Set("onGoMessage", js.Undefined())
+			conn.wsHandlers.Set("onGoClose", js.Undefined())
+		}
+
+		// wsHandlerFn may be zero-value if the pending handler lookup missed.
+		if conn.wsHandlerFn.Truthy() {
+			conn.wsHandlerFn.Release()
+		}
+		if conn.onMessageFn.Truthy() {
+			conn.onMessageFn.Release()
+		}
+		if conn.onCloseFn.Truthy() {
+			conn.onCloseFn.Release()
+		}
+
 		p.mu.Lock()
 		delete(p.activeConnections, conn.id)
+		delete(p.destinations, conn.id)
+		delete(p.pendingHandlers, conn.id)
 		p.mu.Unlock()
+	})
 }
 
 func (p *RDCleanPathProxy) sendToWebSocket(conn *proxyConnection, data []byte) {

client/wasm/internal/ssh/handlers.go

@@ -13,7 +13,7 @@ import (
 func CreateJSInterface(client *Client) js.Value {
 	jsInterface := js.Global().Get("Object").Call("create", js.Null())
 
-	jsInterface.Set("write", js.FuncOf(func(this js.Value, args []js.Value) any {
+	writeFunc := js.FuncOf(func(this js.Value, args []js.Value) any {
 		if len(args) < 1 {
 			return js.ValueOf(false)
 		}
@@ -32,9 +32,10 @@ func CreateJSInterface(client *Client) js.Value {
 
 		_, err := client.Write(bytes)
 		return js.ValueOf(err == nil)
-	}))
+	})
+	jsInterface.Set("write", writeFunc)
 
-	jsInterface.Set("resize", js.FuncOf(func(this js.Value, args []js.Value) any {
+	resizeFunc := js.FuncOf(func(this js.Value, args []js.Value) any {
 		if len(args) < 2 {
 			return js.ValueOf(false)
 		}
@@ -42,14 +43,26 @@ func CreateJSInterface(client *Client) js.Value {
 		rows := args[1].Int()
 		err := client.Resize(cols, rows)
 		return js.ValueOf(err == nil)
-	}))
+	})
+	jsInterface.Set("resize", resizeFunc)
 
-	jsInterface.Set("close", js.FuncOf(func(this js.Value, args []js.Value) any {
+	closeFunc := js.FuncOf(func(this js.Value, args []js.Value) any {
 		client.Close()
 		return js.Undefined()
-	}))
+	})
+	jsInterface.Set("close", closeFunc)
 
-	go readLoop(client, jsInterface)
+	go func() {
+		readLoop(client, jsInterface)
+		// Detach before releasing so late JS calls surface as TypeError instead
+		// of silent "call to released function".
+		jsInterface.Set("write", js.Undefined())
+		jsInterface.Set("resize", js.Undefined())
+		jsInterface.Set("close", js.Undefined())
+		writeFunc.Release()
+		resizeFunc.Release()
+		closeFunc.Release()
+	}()
 
 	return jsInterface
 }